Track Tech Questions and Answers - March 2013

In the Oct. '12 issue of CT (One Hit Too Many), we outlined what had happened to a fellow racer who had encountered too many concussions. That piece provided a lot of educational value for us and hopefully our readership. Now, Dale Earnhardt Jr. has proven to be subject to multiple (more than one) concussions.

As of this writing, Dale is sitting out two races since suffering two concussions within six weeks including his crash at Talladega that caused continual headaches. After consulting with doctors, it was recommended that he take time off to recover. But recovery might not be an appropriate term for a concussion.

If you break an arm or collar bone you will recover, the break will heal and even sometimes be stronger than before. Not so with a concussion. What we know now is that there is an accumulative affect with brain injuries that has to do with both the connection between the brain and the skull, and with the brain tissue itself.

We're not sure a person can "heal" completely from a concussion. The symptoms can go away to where you feel fine, but it becomes easier and easier to have future concussions. If that is the case with Dale Jr., then just as it might be with an athlete with bad knees or a pilot who cannot see well anymore, it might just be time to quit driving.

Big time NASCAR racing is a big time money machine and it's very hard to bring that train to a halt in many cases. The death of a superstar does that immediately, but lesser injuries merely slow down that train. In this case, in my opinion, everyone needs to take a long look at the consequences of continuing down this path. Consider what the fans reaction to the sport would be if, and maybe when, Dale can no longer function normally due to lingering symptoms of having repeated concussions.

Here is a quote from my story, PCS (Post-Concussion Syndrome) is a set of conditions that occurs after a concussion and CTE (Chronic Traumatic Encephalopathy) is the result of multiple concussions and other forms of head injury. Both can last for weeks or months, and in extreme cases, for years as is Jeff's case.

Since that article was published, I have had numerous other drivers tell me stories of their own experiences with PCS and even CTE. It has happed to more people than we know and it will continue to happen to others.

With all of the attention concussion has raised recently related to the NFL and players who have suffered the affects of PCS and CTE, NASCAR has stepped up its already excellent safety program and drivers are being monitored more closely than ever for this problem. Over the years, this group has been a model for other sanctions and racetracks on how to provide a measure of safety and a professional response to driver injury.

We would hope that a group of doctors could be assembled who could formulate a set of rules governing dealing with the progression of concussions for drivers. At some point, we need to say stop. At some point drivers must be overruled and made to quit if the symptoms show a progression toward CTE before that point is reached.

When this issue reaches your mailbox, it will have been several months since Dale resumed his racing, or made the decision to retire. If the later were true, many hard-core fans would be disappointed and some upset. But hopefully they would understand and applaud his brave and sensible choice.

If not, so be it. He has to live out the rest of his life with his decisions, not the fans. They will get used to it and maybe someday come to understand that it took a lot of guts to make the right decision for himself.

If you have comments or questions about this or anything racing related, send them to my email address: Bob.Bolles@sorc.com, or mail can be sent to Circle Track, Senior Tech Editor, 9036 Brittany Way, Tampa, FL 33619.

Fast or Slow Coolant FlowHello! I work with my dad's racing team on the engine side, researching/suggesting components and specifications to ensure the engine holds up, cools well, and makes good power. As such, I enjoy reading Circle Track, it gives me some good insight on the parts, technology, and theory as it applies to cars specifically designed for this type of racing.

But, your Nov. '12 issue has a very glaring error, I hope it's corrected for December. Jim Mcfarland wrote "Cooling for parts life and power." Unfortunately, he included the misguided theory that you can move fluid too fast through the radiator. While I may be nobody in anyone else's eyes, I know this is incorrect. It flies in the face of the realities of the cooling system.

In any case, instead of me arguing it, and explaining the physics, I will point out for your review, that on this very website exactly one year ago, Jeff Huneycutt got it right. I would suggest you have Jim read that article. He might even want to talk with the folks over at Stewart Components to get an even better understanding of why there is no such thing as moving coolant too fast (obviously, as long as the pump isn't cavitating).

I'd appreciate it. This myth has gone on for far too long, and too many people still believe it.-Dorian Yeager

Dorian,
We certainly are investigating this and I will give you a little history of where it came from. And by the way, I took thermodynamics in school some time ago, so I have somewhat of an understanding of heat exchange.

Years ago, Smokey began experimenting with improving cooling in his race engines. Remember that radiators were not as well developed in those days as they are now. He would restrict the flow of coolant and lo and behold, the coolant temperature went down.

I can tell you that in my Jeep, when I get in it on a hot day, if I put the temperature on high and the fan on high, the output is warmer than if I slow the fan speed down. That means that more heat is being removed from the air passing through the cooling radiator of the air conditioner when the air is moving slower.

It's no different in a radiator in your race car. It is true that there might be an optimum speed for the coolant to travel and if you run it through too slowly, the coolant in the engine might gain more heat and be harder to cool. But on the other hand, if you run it too quickly than optimum, it won't have the time to exchange that heat to the outside air before it re-enters the engine block and begins the re-heating cycle again.

What I am saying is that the question is a good one and the answer may not be cut and dried. We need more information and it may be as simple as, our radiators are now so efficient that we can move the coolant more quickly through the radiator than ever before. But I can tell you unequivocally, that at some point in the past, this was not a myth and it definitely worked.

Concussion Response
I just got done reading your article on Jeff ("One Hit Too Many," Oct. '12). Thanks to both of you. That's very good information. I'm an SCCA road racer and suffered a traumatic brain injury (TBI) in 2008 and have been able to get back to racing.

We don't crash as often in road racing but we still crash. I know this, but continue to race. I now have a full containment seat, HANS, changed the design of my rollcage, quality belts, and more.

I started a website that deals with TBI, johnmillsracing.com. I use my racing to give hope to others with TBI. Racing is my life as well. My TBI changed my entire life. I ended up divorced (my choice) but have been lucky enough to continue my job.

I would like to hear your and Jeff's comments about my situation and website.

Thank you,-John Mills

John,
Thanks for writing. Yours is not the only letter I received on this subject and it is the focus of my comments in this section this month.

I think we are all different in our physical makeup and some will be able to deal with concussion better than others. We must evaluate our own situation and make decisions that are right for us. We are not trying to say that everyone will progress into what Jeff has experienced. What we are saying is that it is a possibility and if we can educate drivers to the exact symptoms and progression of those symptoms that may lead to cronic post concussion syndrome, then we will have accomplished our goals.

How To Easily Measure Stagger
I always enjoy your articles. I seem to find something to think about from them. It is good mental exercise for an old mind. It beats doing crossword puzzles.

Please show your new readers why you measure the larger tire first. The pictures in this month's issue ("Stagger," Nov. '12) has them doing fraction calculations in order to get stagger. From 35 years in teaching math and more than 50 years in race cars, fractions are not the strong suit of many people. Newby's will bless you.

A person that might be a good story is Diandra Leslie-Pelecky. She wrote "the Physics of NASCAR" and has been doing a blog called "Building Speed" which I'm sure you have seen on Jayski.-Bob Emmons

Bob,
I will look her up. She is also very involved in the discussion of concussions. I did a story on tires years ago and was over at my friends shop near my home. He said, "Do you want to see an easy way to measure stagger?" And he proceeded to show me what you are talking about.

You first measure your larger tire at the front or back of the car. Then remember that dimension only and wrap the tape around the smaller tire on the other side of the car. Where the larger tire dimension falls from the end of the tape on the smaller tire (the number will overlap past the zero end of tape on the smaller tire), is the stagger amount.

There is no subtracting needed, only the need to remember one number, the larger tire circumference. I have used that method many times and told that story numerous times to many racers. Thanks for reminding me.

Looking For a Clear Answer
I've been reading all your info for a while now. I am trying to wade thru all this roll/moment center info and I still don't see any clear answer. It seems a car with a higher center of gravity should also have a higher RC.

I built a car this winter for what we call the Thundercar class up here in Canada. It has stock suspension pick up points, tube chassis, fiberglass body, and a four-link rear. I opted for a '69 Chevelle front clip and rear pick up points, 6-inch ride height, and 108-inch wheelbase.

We run 3,200 pounds, 55 percent left, 50 percent rear, 8-inch Towel City retreads on Hoosier casings. I bought the big 13/8-inch Hotchkiss sway bar at 540 pounds and have a 600 LF, 650 RF, 200 LR,and 175 RR springs. I've been testing it half the season and no matter what, the front doesn't seem to ever totally hook up. I can make it worse, but never really get rid of the understeer. So, I am wondering about RC location.

The front runners here are saying their roll centers are left of center (metric chassis), and they are fast, but also look like their cars are skating quite often.

The way my outside tires get hot, I think I have too much roll, so wouldn't I need to raise the RC or move it to the right? It is currently about 3.5 inches off the ground, just right of center and only migrates down. I have removed the bumpsteer, and don't have a good method to measure Ackermann.

I was also wondered if the shocks were too stiff, I can't feel the chassis dive or roll while driving. Shock travel is almost an inch on front and almost even with no bar preload, it is loose. Help!

Thanks, -Rick

Rick,
The front roll center should be left of centerline. When the car dives and rolls, the moment center always moves, usually to the right. So, your MC is most likely way to the right when the car is in the turns and that makes the front suspension very stiff.

To measure Ackermann, and I have shown this numerous times in the magazine, string out about ten feet in front of the car from the sides of both front tires. Mark a point on tape n the garage floor. Then turn the wheels and re-string the tires. Measure between the marks on both sides. If the measurement is the same, you have zero Ackermann.

Your car could stand to be up to a half inch difference at 10 feet out with the left turning more than the right, but no more than that.

Also, your crossweight should be around 51.7 to 52.0 with the 50 percent rear weight. If you can, compare the left side tire temperatures and adjust the rear spring split until the left front is the same temperature at the left rear tire. If you can move your MC, you might not need to do anything more to get that LF tire temperature up, it will heat up after the change.